op-node/p2p/gossip - ConfigureGossip overwrites sane defaults with zero values

**Bug Description**

https://github.com/ethereum-optimism/optimism/blob/develop/op-node/p2p/gossip.go#L146
```
params := BuildGlobalGossipParams(rollupCfg)

// override with CLI changes
params.D = p.MeshD
params.Dlo = p.MeshDLo
params.Dhi = p.MeshDHi
params.Dlazy = p.MeshDLazy
```
This sets the params values directly to those passed in. However, if the passed in struct does not have a value explicitly set (eg `MeshDHi`) then the zero value (0 in this case) is used, which replaced the sane default set earlier with `BuildGlobalGossipParams` (12 btw).

**Steps to Reproduce**
n/a - I've given you the exact code that is wrong.

**Expected behavior**
Should only overwrite these values when non-zero

**Environment Information:**
n/a

**Configurations:**
n/a

**Logs:**
n/a

**Additional context**
n/a

---

⚠️ **Notice:** Issues that do not include the following sections will be subject to closure:
- Bug Description
- Steps to Reproduce
- Environment Information

Please ensure all required sections are filled out accurately to expedite the debugging process and improve issue resolution efficiency.

Start at op-node/p2p/gossip.go around ConfigureGossip and BuildGlobalGossipParams. Check the CLI parameter overrides and verify that zero-valued fields preserve the defaults while explicitly provided nonzero values still override them; done means the sane defaults are no longer replaced by zeros.

Written by the indexing model from the issue text.